Soldiers lead the way as Chibok residents carry placards to protest the abduction of the missing schoolgirls, on Saturday in Maiduguri. / STR AFP/Getty Images

by Oren Dorell, USA TODAY

by Oren Dorell, USA TODAY

The Nigerian government was warned hours in advance that Boko Haram was preparing a raid on Chibok, but failed to prevent the kidnapping of more than 300 school girls last month, according to a report released Friday by Amnesty International.

"The fact that Nigerian security forces knew about Boko Haram's impending raid, but failed to take the immediate action needed to stop it, will only amplify the national and international outcry at this horrific crime," said Netsanet Belay, Amnesty International's Africa Director, Research and Advocacy.

The Amnesty report, based on interviews done in Borno State, where the attack occurred, was no surprise to Audu Ogbeh, founder and chieftain of the opposition party All Progressives Congress, who spoke to USA TODAY from the Nigerian capital, Abuja.

"This is what everybody in Borno says, that it has been going on like this for the last year and a half," Ogbeh said. "That intelligence is provided but the military doesn't show up or just walks away."

Borno state Sen. Ahmed Zannah told CNN today that the military sent reinforcements after the raiders arrived in Chibok.

Boko Haram, a radical Islamist terrorist group, is believed to be holding 276 schoolgirls. About 50 of the abducted girls escaped during a night-time raid on a government boarding school in Chibok. The government's tally has grown since the attack was first reported, from around 100.

Boko Haram leader Abubaker Shekau said in a taunting video released to local media Monday that he will sell the girls "in the market." The al Qaeda affiliate seeks to impose its radical interpretation of Islamic law in Nigeria and has killed thousands of people in the past few years in shootings, bombings and arson. Its name means "Western education is forbidden."

Ogbeh, a former national chairman of Nigeria's ruling Peoples Democratic Party but now a member of the political opposition, said Borno officials he has spoken to believe the girls are still being held in the Sambisa Forest Reserve. Sambisa is a large national park where Boko Haram is known to have camps. Local reports have circulated for weeks that village security watch groups had warned the military that militants had gathered and were headed for Chibok, but the government did not respond, he said.

Amnesty says it confirmed that Nigeria's military headquarters in Maiduguri was aware of the impending attack soon after 7:00 p.m. on April 14, close to four hours before Boko Haram began their assault on the town.

Members of civilian patrol groups set up by the government, known as "vigilantes," told Amnesty investigators they made a series of phone calls after a force of heavily armed militants on motorcycles stopped at Gagilam, a neighboring village, and said they were preparing a raid on Chibok.

"An inability to muster troops ­- due to poor resources and a reported fear of engaging with the often better-equipped armed groups - meant that reinforcements were not deployed to Chibok that night," Amnesty said in a statement.

A contingent of 17 army troops and local police tried to repel the attack, but were overpowered and forced to retreat, Amnesty said. One soldier died.

Ogbeh said he finds it "difficult to accept" that an Islamist militant group whose main goal is to wipe out Western education in Nigeria is better equipped than the Nigerian military, which received $4 billion in the past two years.

He welcomed American involvement in the search, and said U.S. aerial and satellite surveillance, electronic monitoring, and armed drones should be brought in to help find their forest hideouts and locate the girls.

"Boko Haram doesn't grow food in that forest and when it rains they become extremely uncomfortable," he said. "They do move around and when they move around they can be engaged."